Hi bh,
What are you listening to: original LP, reissue LP, stereo cd before pitch correction, stereo cd after pitch correction, SACD, mono cd, K2 cd, 32 Ultrabit Cd, Dual Disc CD/DVD?

Where are you hearing the snare "hissing" sound, every track?
I put the Dual Disc version on for variety (haven't played this one in a while) and am listening to the DVD side (48kz/16 bit, on my Cambridge Audio CXU, playing into my Taboo Mk III and Audeze LCD2 headphones) and the snare sounds as it always does to me. There is a sort of sizzle sound which is a ride cymbal that Jimmy almost always plays, it's sort of his signature to have this sprightly ride going on . . . But I don't hear a "hissing" per se. Could it be you're hearing more resolution to the sound now with the new amp and you're hearing that ride sizzling along with the snare?